SPC MESOSCALE DISCUSSION 1567 FOR N CENTRAL SD/S CENTRAL ND...
CONCERNING...SEVERE THUNDERSTORM POTENTIAL...

VALID 192035Z - 192300Z

THUNDERSTORMS MAY INCREASE IN COVERAGE/INTENSITY AND SPREAD NEWD
FROM NRN SD INTO SRN ND IN THE NEXT COUPLE OF HOURS.  THIS AREA IS
BEING MONITORED FOR A POSSIBLE WW.

A SMALL CLUSTER OF STORMS HAS INTENSIFIED RECENTLY IN THE
DEWEY/CORSON COUNTY AREA OF SD...IN ASSOCIATION WITH A WEAK MID/
UPPER LEVEL SPEED MAX MOVING ENEWD TOWARD SRN ND.  THE BOUNDARY
LAYER HAS DESTABILIZED ACROSS MUCH OF CENTRAL/NRN SD IN THE WAKE OF
MORNING THUNDERSTORM OUTFLOW...AND SBCAPE VALUES NOW RANGE FROM
3500-5000 J/KG.  DESTABILIZATION WILL ALSO CONTINUE NWD INTO ND AS
THE WEAKENING COLD POOL OVER SE ND ERODES WITH ADDITIONAL DAYTIME
HEATING...AND THIS WOULD SUPPORT A SEVERE STORM THREAT NEWD INTO
ND.  THE COMBINATION OF STRONG INSTABILITY AND 0-6 KM SHEAR
MAGNITUDES OF 35-40 KT WILL BE SUFFICIENT FOR A FEW SUPERCELLS...
WITH LARGE HAIL AND DAMAGING WINDS THE MAIN THREATS.  GIVEN THE
EXPECTED INCREASE IN STORM COVERAGE THIS AFTERNOON ACROSS NRN
SD/SRN ND...A WW MAY BE NEEDED IN THE NEXT 1-2 HOURS.

..THOMPSON.. 07/19/01